Strong exciton–photon coupling at room temperature in microcavities containing two-dimensional layered perovskite compounds

We have realized Perot–Fabry microcavities containing a two-dimensional layered perovskite-type semiconductor: (C 6 H 5 C 2 H 4 –NH 3 ) 2 PbI 4 between a dielectric mirror and a metallic mirror. A strong coupling regime between the perovskite exciton and the confined photon mode has been evidenced at room temperature from angular-resolved reflectivity experiments, anticrossings as large as 190 meV are observed between the excitonic and cavity modes. We have shown that the design of the microcavity can be varied at will, so that the detuning or the Rabi splitting can be precisely chosen. The emission of the polaritonic low energy branch has been observed.